alpine: pull CC_FOR_BUILD

Without the change alpine build on aarch64-linux fails due to missing
$target-gcc wrapper: https://hydra.nixos.org/build/219995705

checking whether the C compiler works... no
configure: error: in `/build/alpine':
configure: error: C compiler cannot create executables

pkgs/applications/networking/mailreaders/alpine/default.nix

···
-{ lib, stdenv, fetchgit, ncurses, tcl, openssl, pam, libkrb5
-, openldap, libxcrypt, gitUpdater
+{ lib
+, stdenv
+, fetchgit
+, buildPackages
+, ncurses
+, tcl
+, openssl
+, pam
+, libkrb5
+, openldap
+, libxcrypt
+, gitUpdater
 }:
 
 stdenv.mkDerivation rec {
···
     rev = "v${version}";
     hash = "sha256-cJyUBatQBjD6RG+jesJ0JRhWghPRBACc/HQl+2aCTd0=";
   };
+
+  depsBuildBuild = [ buildPackages.stdenv.cc ];
 
   buildInputs = [
     ncurses tcl openssl pam libkrb5 openldap libxcrypt